The attorney for the widow of the dead Boston Marathon bombing suspect says a federal grand jury asked her for items that belonged to one of the victims in a triple slaying in Waltham nearly three years ago.

The attorney for the widow of the dead Boston Marathon bombing suspect says a federal grand jury asked her for items that belonged to one of the victims in a triple slaying in Waltham nearly three years ago.

Katherine Russell's attorney says a grand jury asked her for items that belonged to Brendan Mess, a friend of Tsarnaev's and one of the three people killed in the Waltham triple slaying on Harding Avenue on Sept. 11, 2011. Attorney Amato DeLuca says Russell doesn't have anything that belongs to Mess, who once lived in Cambridge.

The 2011 homicide case in Waltham remains unsolved, though Tsarnaev was fingered in the killings after his death in a post-bombing shootout with police.

Clues in the Waltham killing that might early on have led local investigators to Tsarnaev, who was already on the FBI's radar as a possible religious extremist, raise questions about whether the marathon bombings could have been prevented.

Federal prosecutors in Boston revealed in court documents that Ibragim Todashev, a friend of Tsarnaev's, told authorities he and Tsarnaev participated in the killings in Waltham.